The objectives of this research program are as follows: 1) Studies of the various factors that control the various cardiovascular functions throughout intrauterine life, during the neonatal period and up until the adult state of control patterns are reached. These experiments are carried out on chronically instrumented animals in which the ontogenetic development of the adrenergic, cholinergic and dopaminergic neurohumoral controls are investigated. 2) The role of the neurohumoral controls in the fetal and neonatal responses to various forms of stress such as hypovolemia hypoxia, etc. 3) The changes in the resting cardiovascular functions such as cardiac output, stroke volume and systemic vascular resistances as a function of growth and development. 4) The transplacental transfer of analgesic and tranquilizers and their effects on fetal cardiovasclar functions; and 5) The effects of sex hormones on uteroplacental and fetal circulatory functions and on hormonal production rates.